The invention relates generally to wind power generation, and more particularly to systems and methods for controlling a ramp rate of a wind farm.
A wind power generation system generally includes a wind farm having a plurality of wind turbine generators supplying power to a utility grid. Collective power output of the wind farm is greatly influenced by wind conditions on individual wind turbine generators. Utilities often have other power resources, such as thermal power plants to balance their electrical loads, thus accommodating variability in wind conditions during intermittent wind conditions. Thermal power plants may include, for example, coal and gas fired stations. Power fluctuation of wind farms due to gusty or low wind conditions is usually dealt with by adjusting power output of these thermal power plants to provide relatively constant overall power matching demands.
However, it is often difficult to change power output of thermal power plants instantaneously. Thermal power generators utilize a rate of change of power that does not impose excessive thermal stresses, and that accommodate a plurality of natural lag times involved in heating and cooling a plurality of heat transfer components of the thermal power generators. As an example, coal-fired power stations may take over 12 hours to start from cold, and, even when hot, may take 2 to 3 hours to change from 0-100% of their rated power. Accordingly, rate of change of power used by the thermal power generators cannot be easily controlled.